Apparatus and method for thermal cutting of a workpiece

ABSTRACT

An apparatus for thermal cutting of workpieces includes a cutting means for separating a workpiece into a finished part and a residual part, a workpiece support, and support elements for supporting the workpiece. Separate first and second support elements are provided for adjustable support of the finished part or the residual part and are disposed at a mutual separation in the region of the separating cut.

CLAIM OF PRIORITY

This application claims priority under 35 USC §119(a) to German PatentApplication Serial No. 02003419.5, filed on Feb. 16, 2002, the entirecontents of which is hereby incorporated by reference.

TECHNICAL FIELD

The invention relates to thermal cutting of a workpiece, and moreparticularly to a workpiece support with support elements for supportingthe workpiece during thermal cutting.

BACKGROUND

Laser processing machines are known, for example, German Patent Number19943043 A1.

Laser processing machines with two support levels for transporting aworkpiece are described in JP 61-292988 and in JP 62-275593.

Until now, during thermal cutting of a workpieces, the workpieces to beprocessed have been disposed onto grids or grates of the workpiecesupport, resulting in a grid of support points. This causes thefollowing problems: a kerf in the workpiece for separating the workpieceinto a finished part and a residual part can be formed in the region ofthe support points. This may cause a caking of the two workpiece partssince in addition to the two workpiece parts, the support elements arealso heated and welding can occur. Moreover, the center of mass of thetwo workpiece parts with regard to the support points may be unfavorablesuch that the workpiece parts are tilted on the workpiece support. Theseproblems prevent an automated safe removal of the workpiece parts fromthe workpiece support.

SUMMARY

In a first general aspect, an apparatus for thermal cutting a workpieceincludes a thermal cutting machine that in operation cuts the workpieceinto a finished part and a residual part. A plurality of adjustablesupport elements support the finished part and the residual part. Nosupport elements are located under the region of the workpiece whosetemperature rises substantially when thermally cut.

Embodiments may include one or more of the following features. Forexample, the plurality of support elements may be displaceable. Theplurality of adjustable support elements may include a plurality offirst support elements forming a first support level for supporting thefinished part and a plurality of second support elements forming asecond support level for supporting the residual part. The first supportelements may be adjustable in height, and the second support elementsmay be adjustable in height. A first matrix of first support elementsmay match an area of the finished part and a second matrix of secondsupport elements may match an area of the residual part. A roller may beincluded at a tip of a support element. At least one of the supportelements may include a hydraulically displaceable cylinder. At least oneof the support elements includes a pneumatically displaceable cylinder.A programmable control unit may be included for positioning the supportelements.

In a second general aspect, a method of thermally cutting a workpieceinto a finished part and a residual part includes positioning theworkpiece on a plurality of adjustable support elements, providing afirst subset of support elements from the plurality of support elementsfor supporting the finished part, and providing a second subset ofsupport elements from the plurality of support elements for supportingthe residual part. The first subset of support elements is positioned tosupport the finished part, and the second subset of support elements ispositioned to support the residual part. The workpiece is thermally cutinto the finished part and the residual part by thermal cutting of theworkpiece, but no support elements are located under the region of theworkpiece whose temperature rises substantially when separated by thecutting means.

Embodiments may include one or more of the following features. Forexample, the first subset of support elements and the second set ofsupport elements may be displaced away from the region of the workpiecewhose temperature rises substantially when separated by the cuttingmeans. The first subset of support elements may be positioned at adifferent vertical position than the second subset of support elements.A first matrix of support elements may be provided that matches an areaof the finished part for supporting the finished part, and a secondmatrix of support elements may be provided that matches an area of theresidual part for supporting the residual part. Positioning the firstsubset of support elements may include positioning the support elementswith hydraulic pressure, or with pnuematic pressure. Positioning thesecond subset of support elements may include positioning the supportelements with pnuematic pressure or with hydraulic pressure. A controlsignal may be sent from a programmable control unit to a support elementto control the position of the support elements.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features will be apparent fromthe description and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a longitudinal sectional view of a workpiece support of alaser cutting machine.

FIG. 2 is a top view onto the workpiece support of FIG. 1.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

A workpiece (e.g., a sheet of sheet metal) is placed on a workpiecesupport and subsequently processed by a known thermal cutting means. Thecutting means may be, for example a laser processing machine, which isknown in the art and therefore not shown in FIG. 1. FIG. 1 shows aworkpiece on which several separating cuts were already performed by thelaser cutting means, such that several finished parts 2 a, 2 b, 2 c, and2 d and a residual part 3 were produced. The residual part 3 is notnecessarily waste.

The workpiece support 1 works with a first support level 4 and a secondsupport level 5 such that the finished parts 2 a, 2 b, 2 c, and 2 d areat a raised position compared to the residual part after cutting. Theseparated residual part 3 is in the lower support level 5.

The separated parts 2 a, 2 b, 2 c, and 2 d, and 3 can be easily removedfrom the laser processing machine because the parts 2 a, 2 b, 2 c, and 2d are spatially separated from part 3 and/or caking of the parts 2 a, 2b, 2 c, and 2 d was prevented. The arrangement of the finished parts 2a, 2 b, 2 c, and 2 d, and the residual part 3 in two different supportlevels 4 and 5 after cutting permits automated process-safe removal ofthe finished parts 2 a through 2 d and of the residual part 3 from theworkpiece support 1. It is clear that association of the support levels4 and 5 to the finished parts 2 a, 2 b, 2 c, and 2 d and the residualpart 3 can also be reversed. Removal of the finished parts 2 a, 2 b, 2c, and 2 d and the residual part 3 can be achieved manually or by meansof suction cups (vacuum frame).

The cutting process which leads to the situation shown concernssubstantially the following method steps which must be carried out oneafter the other: initially, the workpiece to be cut is supplied to theworkpiece support 1. This is achieved manually or with a known transportmeans. The workpiece to be cut is subsequently supported only on thefirst support elements 6. The first support elements 6 can be positionedprecisely in three dimensions (height/depth; X, Y direction) such thatmerely the later produced finished parts 2 a, 2 b, 2 c, and 2 d aresupported or borne by the first support elements 6. For sufficientlyuniform support of the produced finished parts 2 a, 2 b, 2 c, and 2 d, asufficient number of first support elements 6 must be provided (possiblyin a grid or matrix arrangement, as shown in FIG. 2). The first supportelements 6 of the matrix arrangement which can be selected and variablyused can be positioned in a defined manner with regard to the finishedparts 2 a, 2 b, 2 c, and 2 d to be produced for uniform support by meansof a programmable control unit. The first support elements 6 arespecifically used at that location where later finished parts 2 a, 2 b,2 c, and 2 d are produced.

For later support of the residual part 3 produced after the separatingcut, second support elements 7 are provided, of which only individualones are shown in FIG. 2. The residual part 3 to be separated is notsupported or borne during the separating cut and can therefore drop ontothe second support elements 7 (support level 5) as separate residualpart 3. The second support elements 7 also may be designed to beadjustable in height and suitable for positioning in the X and Ydirections.

The separating cut of the cutting process divides the workpiece locatedat one support level into parts 2 a, 2 b, 2 c, and 2 d and 3 located attwo support levels. The positions of the first support elements 6 andthe second support elements 7 are selected such that these have aseparation from the separating cut to be performed in order to produce afree kerf between the finished parts 2 a, 2 b, 2 c, and 2 d and theresidual part 3. Thermal cutting of the workpiece cannot produce cakingor welding of the finished parts 2 a, 2 b, 2 c, and d or the residualpart 3 at the support points of the support elements 6 and 7 becauseprocessing of the workpiece always takes place above a free spacebetween the support points. The support elements 6 and 7 can be adjustedto different predetermined regions of the workpiece.

The cut finished parts 2 a, 2 b, 2 c, and 2 d and the residual part 3represent free cut material, which is loosely supported on the supportelements 6 and 7. The separated finished parts 2 a, 2 b, 2 c, and 2 dare supported on the free ends of the first support elements 6, whereasthe separated residual part 3 is located at the free ends of the secondsupport elements 7. The support elements 6 and 7 are formed e.g. bybolts or bars. Alternatively, also pneumatically displaceable cylinderscan be used. Rollers may additionally be inserted into the support tipson which the finished parts 2 a, 2 b, 2 c, and 2 d and the residual part3 are movably supported.

FIG. 2 moreover shows that also smaller areas 8 are cut out of thefinished part 2 a, which are also automatically lowered to the deepersupport level 5 after the separating cut. To remove the residual part 3,it can possibly be cut before removal.

Other Embodiments

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade. Accordingly, other embodiments are within the scope of thefollowing claims.

1. An apparatus for thermal cutting a workpiece comprising: a thermalcutting machine that in operation cuts the workpiece into a finishedpart and a residual part; a plurality of adjustable first supportelements for supporting the finished part at a first support level; anda plurality of adjustable second support elements for supporting theresidual part at a second support level different from the first supportlevel, wherein no support element is located under a region of theworkpiece whose temperature rises substantially when thermally cut. 2.The apparatus of claim 1, wherein the plurality of support elements aredisplaceable.
 3. (canceled)
 4. The apparatus of claim 1, wherein thefirst support elements are adjustable in height.
 5. The apparatus ofclaim 1, wherein the second support elements are adjustable in height.6. The apparatus of claim 1, wherein a first matrix of first supportelements matching an area of the finished part are selectable from theplurality of adjustable support elements for supporting the finishedpart and a second matrix of second support elements matching an area ofthe residual part are selectable from the plurality of adjustablesupport elements for supporting the residual part.
 7. The apparatus ofclaim 1, wherein a roller is included at a tip of a support elementcomprises a roller at a tip of the support element.
 8. The apparatus ofclaim 1, wherein at least one of the support elements includes ahydraulically displaceable cylinder.
 9. The apparatus of claim 1,wherein at least one of the support elements includes a pneumaticallydisplaceable cylinder.
 10. The apparatus of claim 1, further comprisinga programmable control unit for positioning the support elements.11.-17. (canceled)